We propose a 1-year pilot study to evaluate the validity of self-reported exposures to construction work tasks among sheet metal workers. The variable, multiple-task nature of sheet metal work is typical of many other skilled construction trades. Approximately lOO sheet metal workers will be observed for 3 days each. These workers will be asked to complete questionnaires detailing the proportion of time spent at various tasks on the days they are observed. Questionnaires will also ascertain factors such as the gauge and dimensions of sheet metal materials handled. A feedback step will be incorporated after the 1st questionnaire is completed, whereby investigators will meet individually with each worker to compare the results of worker-reported versus observational data. Thus in this study, worker-reported questionnaire data on time spent on tasks will be compared to observational data, and the validity assessed both pre- and post-feedback. The objectives of the proposed study are to: (1) Develop and pretest a self-administered questionnaire which workers will use to report the time spent on sheet metal work tasks, and materials handled. (2) Enroll lOO sheet metal workers into this study. These workers will be employees of three large contractors. (3) Observe study participants to determine the time spent performing various sheet metal work tasks, and materials handled. Have participants complete questionnaires on same day. (4) Provide each participant with feedback on how his/her responses compare with observer data. (5) Observe each participant for two more days. Have each participant complete questionnaire for those days. (6) Compare the data from worker-report method with the observational data to determine the validity of worker-reporting method, both pre-feedback and post-feedback. The ultimate aim of this pilot study is to develop a valid instrument for the collection of self-reported data on duration of exposure to identified work tasks. Such an instrument would be valuable in future epidemiological studies seeking to identify tasks associated with the prevalence and/or severity of musculoskeletal disorders, and also in the evaluation of intervention studies.